Renal Function Analysis Method and Apparatus

Abstract

A method for measuring a glomerular filtration rate in a mammalian kidney comprises a source of reporter and marker fluorescent molecules. The fluorescent molecules are introduced into the blood stream of a mammalian subject. Over a period of time, a measurement of the intensities of the reporter and marker fluorescent molecules is taken. A ratio is calculated to determine the health of the subject's kidney. This method measures volume of plasma distribution based on a fluorescence of a marker molecule relative to a fluorescence of a reporter molecule.

1 . A composition for introduction into a mammalian subject's vascular system to analyze an organ function, the composition comprising:
 a reporter molecule; and   a marker molecule wherein said reporter molecule and said marker molecule share a molecular property, said reporter molecule molecular property having a first quality, and said marker molecule molecular property having a second quality distinguishable from said first quality.   
   
   
       2 . The composition of  claim 1  wherein said molecular property is chosen from a group consisting of molecular weight, size, shape, charge, compound, and radio frequency. 
   
   
       3 . The composition of  claim 1  wherein said reporter molecule has a first fluorescent characteristic, and said marker molecule has a second fluorescent characteristic. 
   
   
       4 . The composition of  claim 1  wherein said reporter molecule has a first fluorescent characteristic, and said marker molecule has a second fluorescent characteristic, and wherein said first fluorescent characteristic and said second fluorescent characteristic are distinguishable. 
   
   
       5 . The composition of  claim 1  wherein said reporter molecule has a first fluorescent characteristic, and said marker molecule has a second fluorescent characteristic, and wherein said first fluorescent characteristic is a first fluorescence excitation wavelength and a first fluorescence emission wavelength said second fluorescent characteristic is a second fluorescence excitation wavelength and a second fluorescence emission wavelength, said first and second fluorescence excitation wavelengths and said first and second fluorescence emission wavelengths being unequal. 
   
   
       6 . The composition of  claim 1  wherein said molecular property is a molecular weight and said reporter molecule has a first molecular weight which is less than a second molecular weight of said marker molecule. 
   
   
       7 . The composition of  claim 6  wherein said second molecular weight is great enough to resist filtration of the marker molecule by a human kidney. 
   
   
       8 . The composition of  claim 6  wherein said first molecular weight is of a magnitude wherein said reporter molecule is filtered by a properly functioning mammalian kidney. 
   
   
       9 . The composition of  claim 6  wherein said first molecular weight is of a magnitude wherein said reporter molecule is readily filtered by a properly functioning mammalian kidney, and wherein said second molecular weight is great enough to resist filtration of the marker molecule by a mammalian kidney. 
   
   
       10 . The composition of  claim 6  wherein said first molecular weight is substantially less than said second molecular weight. 
   
   
       11 . The composition of  claim 6  wherein said first molecular weight is chosen from a group of ranges consisting of 1 kD to 500 kD, 3 kD to 150 kD, 10 kD to 150 kD, 10 kD to 70 kD, and 20 kD to 70 kD. 
   
   
       12 . The composition of  claim 6  wherein said first molecular weight is less than 500 kD. 
   
   
       13 . The composition of  claim 6  wherein said first molecular weight is between 1 kD and 500 kD. 
   
   
       14 . The composition of  claim 6  wherein said first molecular weight is between 3 kD and 150 kD. 
   
   
       15 . The composition of  claim 6  wherein said first molecular weight is between 3 kD and 70 kD. 
   
   
       16 . The composition of  claim 6  wherein said first molecular weight is between 3 kD and 20 kD. 
   
   
       17 . The composition of  claim 6  wherein said first molecular weight is about 5 kD. 
   
   
       18 . The composition of  claim 1  wherein said reporter molecule is a dextran. 
   
   
       19 . The composition of  claim 1  wherein said marker molecule is a dextran. 
   
   
       20 . The composition of  claim 1  wherein said reporter molecule is amino fluorescein dextran. 
   
   
       21 . The composition of  claim 1  wherein said marker molecule is a larger sulforhodamine 101 dextran that is not filtered by the organ. 
   
   
       22 . The composition of  claim 1  wherein said reporter molecule is a fluorescein isothiocyanate-inulin. 
   
   
       23 . The composition of  claim 1  wherein said marker molecule has a glomerular sieving coefficient of about 0. 
   
   
       24 . The composition of  claim 1  wherein said marker molecule is not substantially secreted, reabsorbed, or filtered by a mammalian kidney. 
   
   
       25 . The composition of  claim 1  wherein said marker molecule is not capable of passing through a glomerular filtration barrier. 
   
   
       26 . The composition of  claim 1  wherein said reporter molecule and said marker molecule are dextrans conjugated with a fluorescein. 
   
   
       27 . The composition of  claim 1  wherein said reporter molecule and said marker molecule are dextrans conjugated with a fluorescein, and wherein said reporter molecule fluorescein has a fluorescence excitation wavelength that is not equal to a fluorescence excitation wavelength of said marker molecule. 
   
   
       28 . The composition of  claim 1  wherein said reporter molecule is capable of passing through a glomerular filtration barrier.